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Summary of the impact

Rapid runoff from rural parts of river catchments can pollute downstream
water bodies by
transmitting sediment, agricultural fertiliser, or other pollutants from
extensive diffuse sources, and
can also lead to downstream flooding. Environmental managers often try to
mitigate these
problems by encouraging interventions, such as changes in farming practice
or the construction of
physical obstacles, which delay runoff from rural catchments. DU
geographers have worked with
stakeholders to develop a family of flexible user-friendly computer
modelling tools which predict
and map the likely critical sources of pollution or flooding and the
downstream locations that are
most at risk. This helps environmental managers target the best locations
for intervention and
compare the effects of alternative interventions. The software tools have
been used by regulatory
bodies (e.g. the Environment Agency) and NGOs (e.g. Rivers Trusts) to plan
mitigation works and
benefit local communities and the environment in many parts of England.

Underpinning research

A new approach to modelling catchment processes based on the analysis of
water flow pathways
was developed at Durham by Lane (DU Staff, 2004-11), Reaney (PDRA 2005-7,
RCUK Fellow
2007-2012, Lecturer 2012-), and Milledge (PDRA 2008-9, NERC PDRF 2010-13)
in a 2005-9
NERC knowledge exchange grant to Durham and Lancaster Universities( PI
Lane) with co-funding
from Defra, the Environment Agency, and the Eden Rivers Trust. Subsequent
development and
application has involved the active participation of regulatory agencies
and other stakeholders in
the customisation and application of models, partly within a collaborative
Oxford-Durham-
Newcastle-UEA ESRC/NERC Rural Economy and Land Use (RELU) project on
flooding (Lane co-
I, Odoni PDRA 2007-11 at DU) and also in several Durham-only projects in
2008-11 which were
funded by the Environment Agency, Forest Research, the EU and other
sources; some of these
supported PhD students who contributed to the research and its impact.

The NERC grant developed a software package called SCIMAP, which is short
for Sensitive
Catchment Integrated Modelling And Prediction. The approach utilises
digital elevation models,
land cover maps, hydrological theory, and GIS analysis to map the relative
risk of generating a
`problem' (e.g. rapid runoff, fine sediment, nutrients, or coarse
sediment) at each pixel of the digital
map of a rural area, and the likelihood of the `problem' connecting to a
particular river or lake.
These `problems' are then routed along their individual flow paths into
and along the stream
network, taking into account disconnections and dilution effects, to
predict which parts of the
network are most at risk from the problem. This is scientifically novel in
three ways:

it treats both source risk levels and rapid-flow connectivity as
spatially variable over short
distances (down to as little as 1 m), whereas most previous work
operated at resolutions of order
1 km and either ignored connectivity or treated it in a very simplified
way;

it aims to identify critical source locations of pollution, rather
than precisely predicting a particular
water quality parameter at a vulnerable downstream location;

it can predict the effects of interventions at key source areas or
transmission points.

A second major innovation is the close involvement of stakeholders during
all stages of the model
development and application process. Stakeholders were initially involved
in determining questions
and specifying outputs (e.g. in SCIMAP), but subsequently also suggested
and evaluated
alternative action plans. In the EU-funded Adaptive Land Use for Flood
Alleviation project (PI Lane,
then Reaney), we worked closely with the Eden Rivers Trust to devise ways
to reduce flood risk
with minimal impact on agricultural productivity, thus obtaining
acceptance by farmers. In the RELU
project on flooding in Pickering (North Yorkshire), local stakeholders
worked with academics in
`environmental competency groups' to share local knowledge and co-develop
modelling
approaches that reflected both scientific and local understanding
(Reference 5). The modelling part
of the RELU project was done entirely by DU researchers, who used a
minimum-information
requirement approach based on the analysis of flow pathways to respond to
the competency
groups by devising model variants to evaluate novel upstream flood
mitigation measures, leading
for example to the development of `Bund' and `Overflow' models (References
5 & 6). The flexibility
of the model framework and map-like visualisation of the catchment meant
that stakeholders could
participate directly in the modelling and evaluation process.

References to the research

(Bold denotes Durham University staff at time of research, underline
denotes DU research
student. Journal impact factors and citations are from Web of Science as
of 31/7/2013. All six
papers acknowledge funding from RELU and/or NERC.)

Details of the impact

SCIMAP and the related research described above has delivered a family of
modelling tools for
public agencies and other UK users concerned with river catchment
management. The research
has had impact partly because stakeholders were involved from the outset
but also because its
emphasis on runoff and pollutant sources, connectivity, and risk was in
tune with three policy
drivers which we mention here because they are important context for the
impact.

(1) The UK government's 2004 Foresight Report on flooding, its update in
the 2007 Pitt Review
following widespread flooding that year, and Defra's 2005 policy document
Making space for
water all recognised that upstream interventions in rural catchments
might alleviate flood
generation and transmission and thus reduce the risk at vulnerable
downstream towns. The
Defra document flagged this as a knowledge gap and research priority, and
Defra, the
Environment Agency (EA below), and Natural England subsequently funded
three `Slowing the
Flow' pilot projects in 2009-2011. Pickering was chosen as one of the
sites, partly because of
the work already done by DU (Source 1, p.10).

(2) The European Union's Water Framework Directive, adopted in 2000,
requires member states
to assess the environmental quality of all rivers and other water bodies
by December 2013 and
have improvement plans in place by 2015. In England and Wales the status
assessment is
being done by the EA, which is consequently having to devote considerable
effort to mapping
diffuse pollution (mostly farming-related) in rural catchments in addition
to its longstanding
responsibility for licensing or penalising pollution from major point
sources such as industry and
sewage works.

(3) Reducing diffuse pollution from agricultural fertilisers is also the
driver for the ongoing Defra-
funded EA/Natural England Catchment Sensitive Farming initiative, which
started in 2006 and
offers grants and advice to farmers in almost half of England.

Flooding: the RELU project led to new ideas on how to alleviate
flood risk at Pickering
(References 5, 6) by small-scale interventions at key locations within the
catchment. Following
endorsement of these ideas by the local councils, we helped plan their
implementation in
collaboration with Forest Research and a local community group (the
Ryedale Flood Research
Group, established during the RELU project). Our `Bund' and `Overflow'
models were used in
2009-2011 for detailed planning of a package of interventions. These
include tree planting,
blocking moorland drains, building artificial logjams in small forested
tributary streams to add to
those formed naturally by tree fall, and constructing low earth dams
(bunds) across stream
floodplains near Pickering. The final Forest Research/Defra report on the
project highlights the
value of the modelling in identifying the most effective locations for
intervention (Source 1, p.13).

Most of the measures have now been implemented, but additional modelling
led to a
preference for fewer but larger bunds. The North York Moors Park Authority
approved the bund
plans in May 2013. Source 1 states (p.7) that "Slowing the Flow at
Pickering has gained a national
profile [and has helped] guide and integrate the implementation of
government policy on flood risk
and land use management". Source 1 (p.7) also notes that the project
"succeeded in fully engaging
the local community, who have largely embraced the concept of a
whole-catchment approach to
flood risk management", and this assessment is endorsed by community
groups (Source 2). A
spokesperson for the Ryedale Flood Research Group testifies that "the RFRG
project was critical
in listening to local opinion and expertise, effectively developing it
into a `feasibility study', then
providing the credibility for ideas to be taken further. The role of flood
scientists from Durham
played a key part in this ... both [through] flood modelling and by
providing a sound learning
experience" (Source 2).

Diffuse pollution: from 2005 onwards successive versions of the
SCIMAP model have been
embedded in an open-source GIS, freely downloadable under a Creative
Commons licence, with
user-friendly visual interface. The software and training resources are
freely available at
www.scimap.org.uk. In the year to
mid-April 2013 the website had over 1500 visitors (33% of them
from outside the UK) and there were over 200 downloads of the software.
Within the REF period
we have organised and run training events for over 70 managers and
practitioners from rivers
trusts, national and regional EA offices, Defra, and the Scottish
Environmental Protection Agency
(SEPA). We also organised, with EA support, an inaugural user group
meeting for 30 participants
in October 2012 and have prepared downloadable videos and training
documents for those unable
to attend training in person.

SCIMAP is relevant to the EA's work on the Water Framework Directive and
Catchment-
Sensitive Farming initiative because the model can predict not only which
stretches of stream or
river are at greatest risk from diffuse pollution, but also where the
likely critical source areas are.
By late 2012 EA officers trained by DU had used the model to produce risk
maps for phosphorus
and fine sediment (two of the main causes of failure to reach WFD `good'
status) in 11 top-priority
Catchment-Sensitive Farming catchments distributed throughout England,
Wales and the Scottish
Borders. SCIMAP is now mounted on the EA's central modelling platform so
that it is available to
all EA staff. The EA keynote speaker at the October 2012 user group
meeting stated that the EA
found SCIMAP useful because it could interface with existing
national-scale datasets, is
computationally efficient, has easily-understood output, and helps target
source areas for detailed
inspection on the ground (Source 3). The Irish agricultural authority
(Teagasc) has used elements
of SCIMAP in six catchments, and SCIMAP is being used for characterisation
of fine sediment and
phosphorus pollution and assessment of test mitigation measures in Defra's
£2m 2009-2014 Eden
Demonstration Test Catchment project.

The other main users of SCIMAP are Rivers Trusts: charitable
organisations which make
practical catchment and river improvements in the interests of anglers,
riparian landowners and
other river users in all parts of the UK (www.theriverstrust.org/riverstrusts/trust_movement.html).
SCIMAP
has been attractive to Rivers Trusts because, as Source 4 puts it,
"[unlike some models] it
supports knowledge collection and delivery on the ground rather than
trying to circumvent it".

The first collaboration, during the original SCIMAP grant which spanned
the start of the REF
period, was with the Eden Rivers Trust. It changed the Trust's approach to
land management
within 2300 km2 of NW England: the Trust had previously focused
on the main river and river-bank
areas, but now considers the pressures on river ecology and fisheries as
diffuse-source problems
(Source 4). Since 2008 the Trust has liaised with farmers to reduce soil
compaction at critical
sources of flood runoff and to plant trees at key transmission points.

This collaboration with Eden Rivers Trust provided a pathway to broader
impact, with nine other
Rivers Trusts subsequently using SCIMAP to understand the hydrology of
individual catchments
and to plan effective interventions to reduce flooding and/or pollution.
For example, the Yorkshire
Dales Rivers Trust funded a DU PhD project which used SCIMAP to produce
source connectivity
and erosion risk maps in the Ripon multi-objective project, where
interventions such as hedge
planting to trap floodwaters and allow sediment to drop out have led to
"massive improvements" in
managing diffuse pollution across an area of 140km2
to the west of Ripon (Source 5).

As a final example, the Westcountry Rivers Trust has used SCIMAP in its
contribution to South
West Water's 5 year £3m `Upstream thinking' initiative, which will save
the water company money
by reducing treatment costs when it draws sediment-laden water directly
from rivers. As one of the
Trust's officers puts it (Source 6): "The model helps us to quantify the
scale of the problem and
target high-risk areas .... Putting our farm advisors and our capital
investment into the right bits of
the catchment to achieve the most possible benefit". As well as this
application specifically to fine
sediment, the Westcountry Rivers Trust has used the hydrological core of
the model in ecosystem
services work with farmers who are considering planting trees on low-grade
wet land in order to
receive carbon sequestration payments. Source 6 reports a farmer being
shown SCIMAP maps as
part of a multi-agency farm visit and saying "how did you possibly know
where those wet bits
were? Because by looking at them in dry weather you'd never know that when
it rains they become
really boggy". In this and other ways SCIMAP was regarded by this user as
"a powerful tool for
engaging and communicating these issues to stakeholders" (Source 6).